1) Aurin tricarboxylic acid (ATA) is able to inhibit the binding of 125-I- rHuIFN-alpha2b to cell surface receptors of Daudi cells (DWT-sensitive) in a dose dependent manner by pretreating cell culture at room temperature. Total binding and specific binding were decreasing significantly along with the increased dose of ATA, whereas non-specific binding was increasing steadily at both higher and lower concentrations of added 125-I-rHuIFN-alpha2b. 2) The effects of Evans Blue, DGA, Dextran S04 and Na Heparin on the bindin of 125-I-rHuIFN-alpha2b to cell surface receptor of Daudi cells is not significant.